如何使用PHP添加空div

I have 27 records on three pages in PHP. On each page I add an empty <div> in cross direction as it can be seen on the image below.

$keys = 1;
foreach ($fetrecords as $recVals) {
    if ($keys == 3 || $keys == 5 || $keys == 7) {    
        echo '<div id = "emptydiv">test</div>';
    } else {    
        echo '<div id = "mainarticles">code</div>';
    }

    $keys++;
}

<?php
$keys=1;

foreach($fetrecords as $recVals):

    if($keys == 3 || $keys == 5 || $keys == 7):
        echo '<div id="emptydiv">test</div>';
    else :
        echo '<div id="mainarticles">code</div>';
    endif

    $keys++;

    if($keys == 8)
        $keys = 1;

endforeach;
?>

as i think your desire output for all 3 pages.